miR-143 Regulates Lysosomal Enzyme Transport across the Blood-Brain Barrier and Transforms CNS Treatment for Mucopolysaccharidosis Type I

Cation-independent mannose 6-phosphate receptor: From roles and functions to targeted therapies

The cation-independent mannose 6-phosphate receptor (CI-M6PR) is a ubiquitous transmembrane receptor whose main intracellular role is to direct enzymes carrying mannose 6-phosphate moieties to lysosomal compartments. Recently, the small membrane-bound portion of this receptor has appeared to be implicated in numerous pathophysiological processes. This review presents an overview of the main ligand partners and the roles of CI-M6PR in lysosomal storage diseases, neurology, immunology and cancer fields. Moreover, this membrane receptor has already been noted for its strong potential in therapeutic applications thanks to its cellular internalization activity and its ability to address pathogenic factors to lysosomes for degradation. A number of therapeutic delivery approaches using CI-M6PR, in particular with enzymes, antibodies or nanoparticles, are currently being proposed.

Development of a method for isolating brain capillaries from a single neonatal mouse brain and comparison of proteomic profiles between neonatal and adult brain capillaries

BACKGROUND

The functions and protein expressions of the blood-brain barrier are changed throughout brain development following birth. This study aimed to develop a method to isolate brain capillaries from a single frozen neonatal mouse brain and elucidate the enrichment of brain capillaries by quantitative proteomic analysis. We further compared the expression profile of proteins between neonatal and adult brain capillary fractions.

METHODS

The brain capillary fraction was prepared by the optimized method from a single frozen mouse neonatal brain on postnatal day 7. The brain capillary fractions and brain lysates were digested by trypsin and analyzed by liquid chromatography-mass spectrometry for quantitative proteomics.

RESULTS

By optimizing the isolation method, we observed brain capillaries in the fraction prepared from a single neonatal mouse brain (nBC fraction). A protein amount of 31.5 μg, which is enough for proteomic analysis, was recovered from the nBC fraction. By proteomics analysis, the brain capillary selective proteins, including Abcb1a/Mdr1, Slc2a1/Glut1, Claudin-5, and Pecam-1, were found to be concentrated > 13.4-fold more in nBC fractions than in whole brain lysates. The marker proteins for neurons and astrocytes were not concentrated in nBC fractions, while those of pericytes and microglia were concentrated. Compared to adult mouse brain capillary fractions (aBC fractions), the expressions of Abcb1a/Mdr1a, Abcc4/Mrp4, and Slc2a1/Glut1 were significantly lower in nBC fractions than in aBC fractions, whereas those of Slc1a4/Asct1, Slc1a5/Asct2, Slc7a1/Cat1, and Slc16a1/Mct1 were significantly higher. Amino acid transporters, Slc38a5/Snat5, showed the greatest nBC-to-aBC ratio among transporters (9.83-fold). Network analysis of proteins expressed differentially between nBC and aBC fractions revealed that the proteins with terms related to the extracellular matrix were enriched.

CONCLUSIONS

We succeeded in isolating brain capillaries from a single frozen brain of a neonatal mouse at postnatal day 7. Proteomic analysis revealed the differential expression in brain capillaries between neonatal and adult mice. Specifically, amino acid transporters, including Slc1a5/Asct2 and Slc38a5/Snat5, were found to be induced in neonatal brain capillaries. The present isolation method will promote the study of the function and expression of the neonatal blood-brain barrier.

Non-coding RNAs in stroke pathology, diagnostics, and therapeutics

Ischemic stroke is a leading cause of death and disability worldwide. Methods to alleviate functional deficits after ischemic stroke focus on restoration of cerebral blood flow to the affected area. However, pharmacological or surgical methods such as thrombolysis and thrombectomy have a narrow effective window. Harnessing and manipulating neurochemical processes of recovery may provide an alternative to these methods. Recently, non-coding RNA (ncRNA) have been increasingly investigated for their contributions to the pathology of diseases and potential for diagnostic and therapeutic applications. Here we will review several ncRNA - H19, MALAT1, ANRIL, NEAT1, pseudogenes, small nucleolar RNA, piwi-interacting RNA and circular RNA - and their involvement in stroke pathology. We also examine these ncRNA as potential diagnostic biomarkers, particularly in circulating blood, and as targets for therapeutic interventions. An important aspect of this is a discussion of potential methods of treatment delivery to allow for targeting of interventions past the blood-brain barrier, including lipid nanoparticles, polymer nanoparticles, and viral and non-viral vectors. Overall, several long non-coding RNA (lncRNA) discussed here have strong implications for the development of pathology and functional recovery after ischemic stroke. LncRNAs H19 and ANRIL show potential as diagnostic biomarkers, while H19 and MALAT1 may prove to be effective therapeutics for both minimising damage as well as promoting recovery. Other ncRNA have also been implicated in ischemic stroke but are currently too poorly understood to make inferences for diagnosis or treatment. Whilst the field of ncRNAs is relatively new, significant work has already highlighted that ncRNAs represent a promising novel investigative tool for understanding stroke pathology, could be used as diagnostic biomarkers, and as targets for therapeutic interventions.

New function of a well-known promoter: Enhancer activity of minimal CMV promoter enables efficient dual-cassette transgene expression

BACKGROUND

Co-expression of multiple genes in single vectors has achieved varying degrees of success by employing two promoters and/or application of viral 2A-peptide or the internal ribosome entry-site (IRES). However, promoter interference, potential functional-interruption of expressed-proteins by 2A-generated residual peptides or weaker translation of IRES-mediated downstream genes has curtailed their utilization. Thus, there is the need for single vectors that robustly express multiple proteins for enhanced gene therapy applications.

METHODS

We engineered lentiviral-vectors for dual-cassette expression of green fluorescent protein and mCherry in uni- or bidirectional architectures using the short-version (Es) of elongation factor 1α (EF) promoter and simian virus 40 promoter (Sv). The regulatory function of a core fragment (cC) from human cytomegalovirus promoter was investigated with cell-lineage specificity in NIH3T3 (fibroblast) and hematopoietic cell lines U937 (monocyte/macrophage), LCL (lymphoid), DAMI (megakaryocyte) and MEL (erythroid).

RESULTS

The cC element in reverse-orientation not only boosted upstream Es promoter to levels comparable to full-length EF in DAMI, U937 and 3T3 cells, but also blocked the suppression of downstream Sv promoter by Es in U937 and 3T3 cells with further improved Sv activity in DAMI cells. Such lineage-restricted up-regulation is likely attributed to two protein-binding domains of cC and diverse expression of related factors in different cell types for enhancer and terminator activities, but not spacing function.

CONCLUSIONS

Such a newly developed dual-cassette vector could be advantageous, particularly in hematopoietic cell-mediated gene/cancer therapy, by allowing for independent and robust co-expression of therapeutic gene(s) and/or a selectable gene or imaging marker in the same cells.